1. Field of the Invention
This invention relates to a method for the manufacture of waterproof fibrous plates usable as an expansible sealant plate for concrete joints and as floorings for buildings, core materials for tatami mats, substrates for walls, and insulating liners for roofings as well.
2. Description of the Prior Art
Generally various joints are formed in wide concrete pavements for roads, airfields, factories, and cargo yards and in concrete structures such as buildings, dams and embankments. Since such joints are expected to repel foreign matter and retain flatness of surface and, at the same time, prevent rainwater from seeping into roadbeds, adoption of injected joint materials and molded joint plates has prevailed to date. The molded joint plates so used include bituminous molded joint plates (widely known as "elastite") which are produced by kneading a bituminous substance represented by petroleum asphalt with a filler under application of heat, molding the resultant mixture in the shape of plates, and covering the opposite surfaces of such plates with asphalt paper, bituminous fibrous joint plates which are produced by impregnating fibrous plates as with thermally melted petroleum asphalt or cutback asphalt prepared by dissolving and dispersing petroleum asphalt in a petrolic solvent, and foamed joint plates which are produced by foaming resin or rubber. Most of these conventional joint plates have fine properties and poor properties at the same time. Although the bituminous joint plates are economical from the viewpoint of cost, they have a disadvantage in that they conspicuously protrude from concrete pavements owing to expansion or shrinkage of concrete slabs, suffer from heavy changes in properties due to changes of weather conditions, and exhibit very poor resiliency. The foamed joint plates made of synthetic resin enjoy high resiliency and refrain from notably protruding from concrete pavements. They nevertheless have a disadvantage in that they exhibit insufficient rigidity and consequently inferior workability, possess low compressive strength, and therefore fail to keep their original thickness intact under pressure from concrete slabs.
The bituminous fibrous joint plates produced by the impregnation of fibrous plates with thermally melted asphalt, a method heretofore generally accepted are improved in part over the bituminous joint plates. Owing to the impregnation with the asphalt, they inevitably have high asphalt content and great weight. In terms of resiliency, protrusiveness, etc., they are more or less inferior to the resin-containing foamed joint plates.
The bituminous fibrous joint plates produced by another method, i.e. the impregnation of fibrous plates with cutback asphalt prepared by kneading asphalt with a petroleum solvent have the possibility fo catching fire during their actual use in concrete pavements and concrete structures and prove costly because of the high price of petroleum raw materials. owing to insufficient content of bituminous component and excessive capacity for water absorption, they do not pass the specification of ASTM D-1751-73.
As described above, the existing waterproof fibrous plates are now extensively used as sealant plates for concrete joints and as floorings in buildings, core materials for tatami mats, substrates for walls, and insulating lines for roofings as well. To satisfy such extensive applications, the waterproof fibrous plates must excel in waterproofness, insulating property, corrosionproofness, and weatherability, possess resiliency, be light weight and permit easy handling.